Of the handful of 18th century novels I've read in the past two years, Tom Jones is the first I've enjoyed with the fewest qualifications to that word. Fielding is the first English novelist to understand how a story is supposed to work. Sterne's Tristram Shandy was more interested in its own cleverness than including the reader in the joke; Richardson's Pamela is drivel; and the candidates for first novel ever! are worth reading but Gulliver's Travels
and Robinson Crusoe fail to carry a narrative from start to finish.
Fielding throws a lot in the air over this nearly 900 page novel and, with a notably boring exception (I'm looking at you Man of the Hill), the characters and their stories contribute towards the goal of illustrating Tom and Sophia's separate journeys to London with all the misunderstandings, plot twists and gross-out surprises that keep a reader interested. Here is a comic novel that is still capable of real humor and sustaining it. The plot is dense with pratfalls and fists and mistaken identities - a lie told by one character causes misfortune for another which prevents a third from bringing one of the pins from crashing to the floor.
On a serious note, the novel is concerned with hypocrisy more than anything else. Master Blifil and Thwackem in the eyes of the world are respectable, but their platitudes have no feeling behind them, their greed is so blinding they fail to see any other motivation in those around them. Hypocrisy towards sexual desire is thornier territory, but the message can be a simple as its natural, everyone wants to do it anyway, and if all participants have honest expectations and intentions and, erm, no one gets pregnant, its a good time for everybody. Thorny.
The novel works. There are a few moral wrinkles and unnecessary asides and structural problems, but Tom Jones works. I'd recommend it over many others.